The subject matter described herein relates generally to methods and systems for monitoring hot gas path component conditions, and more specifically, to methods for monitoring temperature and strain of hot gas path components using a ceramic-based sensor material composition.
Higher operating temperatures for gas turbine engines are continuously sought in order to increase their efficiency. However, as operating temperatures increase, the high temperature durability of the components of the engine must correspondingly increase. The operating environment within the gas turbine engine is both thermally and chemically hostile and deleterious to certain engine components. If the components are located in certain sections of the engine such as the combustors or high pressure turbine, they generally cannot withstand long service exposure. Typically the surfaces of these components are coated with a protective system, such as a thermal barrier coating (TBC) or an environmental barrier coating (EBC). Generally, a TBC includes an environmentally-resistant bond coat layer and a TBC layer of a ceramic material applied as a topcoat over the bond coat. An EBC, similarly, often includes various material layer combinations including a bond coat layer and an outer layer.
Increased power output of a gas turbine is achieved by heating the gas flowing through the combustion section to as high a temperature as is feasible. However, the heated gas also heats the various turbine components as it flows through the turbine. These turbine components have a direct impact on the operation and efficiency of the turbine. With time, continued flow of excessively high temperature air wears down the component protective TBC layer and the EBC outer layer.
Some known coating life monitoring methods are based on average effects of stress and temperature profiles of all the parts in the turbine engine. These methods, however, are typically unable to focus on individual parts because they do not take into account the exposure circumstances of a particular part or section of a part. A particular part or section of a part may uniquely encounter excessive stress or damage caused by foreign objects, varying operating conditions from site to site, and turbine over-firing. Such circumstances can uniquely influence part life. However, monitoring a particular part that may be subjected to a local heating that is not represented by an overall system temperature is very difficult.